Upgrade notice for ArbOS 61

ArbOS 61 "Elara" will be activated on the Arbitrum Sepolia, Arbitrum One, and Arbitrum Nova chains.

Actions required for node operators

Sepolia network

On Monday, June 29, 2026, at 15:00 UTC, ArbOS 61 is scheduled to activate on the Arbitrum Sepolia chain.

Arbitrum Sepolia node operators must upgrade to Nitro v3.11 ahead of this activation to continue syncing the chain.

• Docker image: offchainlabs/nitro-node:v3.11.0-a618155
• Release notes: https://github.com/OffchainLabs/nitro/releases/tag/v3.11.0

Important dates

The following dates are relevant for Arbitrum chain operators.

Date	Network upgrade	Affected audience
Monday, June 29, 2026 at 15:00 UTC	Arbitrum Sepolia upgrade to ArbOS 61	Node operators running Arbitrum Sepolia

Context

ArbOS 61 "Elara" builds upon ArbOS 51 "Dia". It introduces a set of protocol upgrades to Arbitrum One and Nova, including support for Dynamic Pricing (multidimensional gas pricing), increased Stylus contract size limits, and new mechanisms for managing minimum base fees.

While Dynamic Pricing is included in this release, it will remain disabled at the time of activation. This is because ongoing analyses - led by Offchain Labs in collaboration with Entropy Advisors- have not yet finalized the appropriate gas target parameters required for safe and effective enablement.

The ArbOS 61 governance temperature check has already passed successfully. Upstream governance for ArbOS 61 follows the standard process, including Snapshot temperature checks and an on-chain vote prior to activation on Arbitrum One and Nova.